This invention relates to improvements in a seat reclining apparatus for a vehicle, in which an electrically operated type-seat reclining apparatus provided with a forward-inclination mechanism is arranged to be the same in basic arrangement as a manually operated type-seat reclining apparatus thereby to enable commonality of most of components.
In a seat reclining apparatus for a vehicle, a differentially transmitting mechanism (or a differential gear) is employed as a mechanism for adjusting the angle of inclination of a back seat, so that the back seat can be electrically and rotationally moved at a high reduction ratio.
A seat reclining apparatus for a vehicle, employing the arrangement of the differentially transmitting mechanism, is disclosed in Japanese Patent Provisional Publication No. 2005-278983. In addition to an operation for changing the angle of inclination of the seat back, this seat reclining apparatus for the vehicle is further adapted to instantaneously make the seat back fall forward, for example, when an occupant gets on a two door or coupe type vehicle to take a rear seat from a front door (or when an occupant in the rear seat gets off such a vehicle at the front door). This seat reclining apparatus is arranged as follows.
The commonly known seat reclining apparatus as disclosed in the above patent publication is arranged including: a base plate provided on a seat cushion side; an outer toothed plate attached through an eccentric shaft in such a manner as to be rotatable relative to the base plate and not to be eccentric relative to the base plate, and having external teeth; an inner toothed plate having internal teeth including one or two more number of teeth than the outer toothed plate; an arm plate provided to be integral with the inner toothed plate and attached to a seat back; and a motor provided to the seat back for driving the eccentric shaft. The eccentric shaft has eccentric sections supporting the inner toothed plate and the arm plate eccentrically rotatable relative to the outer toothed plate, and is to move a mesh portion (where the inner toothed plate is meshed with the outer toothed plate) along the circumference.
In the above-discussed seat reclining apparatus, the base plate and the outer toothed plate are in a relationship, in which a first pin and a latch plate are brought into contact with two extending parts of the outer toothed plate so as to lock the outer toothed plate. Further, a relationship among the outer toothed plate, the inner toothed plate and the arm plate is such as to be able to rotate the inner toothed plate and the arm plate together within a range in which second and third pins can be brought into contact with the two extending parts.
More specifically, when an operation is carried out for changing the angle of inclination of the seat back, the outer toothed plate is locked by the first pin and the latch plate, and additionally the inner toothed plate and the arm plate are rotated relative to the outer toothed plate in either of two directions by the motor and a differentially transmitting mechanism. In another operation for inclining the seat back to fall forward, the latch plate is rotated to release the outer toothed plate, thereby allowing the inner toothed plate and the arm plate to fall forward together with the outer toothed plate. When the seat back is pulled to be raised up, the inner toothed plate and the arm plate are pulled to be raised up while the outer toothed plate is rotated back into position. With this, the latch plate is reset so as to lock the outer toothed plate again.